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help with stream files

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Join Date: Jan 2008

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lmastex

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help with stream files

Sep 26th, 2008

Hey again!

This time I have this program which is supposed to read some stream file called "numbers.dat" which has the numbers 1 up to 10.
I get the reading, but the thing is in the for loop I want to add the numbers in circles.
For example:
1 2 3 4 5 6 7 8 9 10
I want the number 1 and number 10 to be added, then number 2 and number 9 to be added.
This addition I want to write it in the stream file called "numbers2.dat"
The program does add the numbers, but in parallel: 1+2 = 3, then 3+4=7

Here is the code.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
 
  #include <fstream>
  #include <iostream>
  #include <string>
 
 using namespace std;
 
 int main() {
 
  int size = 100;
  int pos = 0;
  int largo = 0;
  int dato, dato2, circulo, i;
  int array[size];
 
 ifstream read("numbers.dat");
 ofstream write("numbers2.dat");
 
read >> dato >> dato2;
 
  while (!read.eof()) {
 
   array[pos] = dato; // first number of the file
   array[size-pos-1]= dato2; // last number of the file
 
  pos++;
  largo += 2; // how many elements are in the file
 
  read >> dato >> dato2;
 
 }
 
 circulo = largo/2; // the actual number of circles
 
 write << "LA SUMA DE TODOS LOS CIRCULOS ES: " << endl;
 
 for (i = 0; i <= circulo; i++) {
 
 write << "\ncirculo # " << (i+1) << ": " << dato+dato2; // write to "numbers2.dat" the addition in circles
 
 }
 
  return 0;
 
 }
 
  #include <fstream>
  #include <iostream>
  #include <string>
 
 using namespace std;

 int main() {

  int size = 100;
  int pos = 0;
  int largo = 0;
  int dato, dato2, circulo, i;
  int array[size];
  
 ifstream read("numbers.dat");
 ofstream write("numbers2.dat");

read >> dato >> dato2;

  while (!read.eof()) {

   array[pos] = dato; // first number of the file
   array[size-pos-1]= dato2; // last number of the file
   
  pos++;
  largo += 2; // how many elements are in the file

  read >> dato >> dato2;

 }

 circulo = largo/2; // the actual number of circles

 write << "LA SUMA DE TODOS LOS CIRCULOS ES: " << endl;

 for (i = 0; i <= circulo; i++) {

 write << "\ncirculo # " << (i+1) << ": " << dato+dato2; // write to "numbers2.dat" the addition in circles

 }

  return 0;

 }

So, could you guys give me a hint or is there some way to make the addition in circles? I think I have it already but there's some kind of mistake somewhere. Thanks!

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Join Date: Aug 2005

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Ancient Dragon Ancient Dragon is offline

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Re: help with stream files

Sep 26th, 2008

1) the read loop is all screwed up

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
int pos = 0;
while( read >> array[pos] )
   pos++;
// now that you have all the numbers in an array, just add them
// up the way you want them
int pos = 0;
while( read >> array[pos] )
   pos++;
// now that you have all the numbers in an array, just add them
// up the way you want them

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Join Date: Dec 2006

Posts: 1,089

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vijayan121 vijayan121 is offline

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Re: help with stream files

Sep 26th, 2008

in adition, change int size = 100; to const int size = 100; size of an array must be a constant known at compile time.

Last edited by vijayan121; Sep 26th, 2008 at 1:58 am.

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Join Date: Jan 2008

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lmastex

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Re: help with stream files

Sep 28th, 2008

•

Originally Posted by Ancient Dragon

1) the read loop is all screwed up
Help with Code Tags

C++ Syntax (Toggle Plain Text)
int pos = 0;
while( read >> array[pos] )
   pos++;
// now that you have all the numbers in an array, just add them
// up the way you want them
int pos = 0; while( read >> array[pos] ) pos++; // now that you have all the numbers in an array, just add them // up the way you want them

You mean I need to replace this with the whole read loop? And what about the dato and dato2
int variables? I want them to read them (the numbers in the file) and save them into these variables.

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Re: help with stream files

Sep 28th, 2008

you don't need dato and dato2 because the code you posted does nothing with them. You could modify the code I posted like this:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
int pos = 0;
while( read >> array[pos]  >> array[size-pos-1])
{
   pos++;
   largo += 2; // how many elements are in the file
}
// now that you have all the numbers in an array, just add them
// up the way you want them
int pos = 0;
while( read >> array[pos]  >> array[size-pos-1])
{
   pos++;
   largo += 2; // how many elements are in the file
}
// now that you have all the numbers in an array, just add them
// up the way you want them

Last edited by Ancient Dragon; Sep 28th, 2008 at 9:58 pm.

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Join Date: Jan 2008

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lmastex

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Re: help with stream files

Sep 29th, 2008

Ok, I replaced the code with the one you gave me. I have this now:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
  #include <fstream>
  #include <iostream>
  #include <string>
 
 using namespace std;
 
 int main() {
 
  int i, circulo;
  const int size = 100;
  int pos = 0;
  int largo = 0;
  int array[size];
 
 ifstream read("numbers.dat");
 ofstream write("numbers2.dat");
 
  while( read >> array[pos]  >> array[size-pos-1])
 
{
   pos++;
 
   largo += 2;
 
}
 
 circulo = largo/2;
 
 write << "LA SUMA DE TODOS LOS CIRCULOS ES: " << endl;
 
 for (i = 0; i <= circulo; i++) {
 
 write << "\ncirculo # " << (i+1) << ": " << array[pos]+array[size-pos-1];
 
 }
 
  return 0;
 
 }
  #include <fstream>
  #include <iostream>
  #include <string>
 
 using namespace std;

 int main() {

  int i, circulo;
  const int size = 100;
  int pos = 0;
  int largo = 0;
  int array[size];
  
 ifstream read("numbers.dat");
 ofstream write("numbers2.dat");

  while( read >> array[pos]  >> array[size-pos-1])

{
   pos++;

   largo += 2;

}

 circulo = largo/2;

 write << "LA SUMA DE TODOS LOS CIRCULOS ES: " << endl;

 for (i = 0; i <= circulo; i++) {

 write << "\ncirculo # " << (i+1) << ": " << array[pos]+array[size-pos-1];

 }

  return 0;

 }

This is what I get in the output of the file:

LA SUMA DE TODOS LOS CIRCULOS ES:

circulo # 1: 6822532
circulo # 2: 6822532
circulo # 3: 6822532
circulo # 4: 6822532
circulo # 5: 6822532
circulo # 6: 6822532

What am I doing wrong?

Last edited by lmastex; Sep 29th, 2008 at 12:31 am.

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Re: help with stream files

Sep 29th, 2008

>>write << "\ncirculo # " << (i+1) << ": " << array[pos]+array[size-pos-1];

Variable pos is never changed. I think you should use the loop counter instead of pos.

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